On 17/07/17 10:53, Christoph Hellwig wrote:
I still haven't gotten hold of an i915 machine where I could run the actua ltest suite. But I did some audit of the code, and it seems blk-mq is lacking support for the RQF_PM flag. While I can't directly see how this would cause the hang your caused it's a least easy to test. Can you apply the patch below and test with the use_blk_mq=0 parameter? Note that implementing RQF_PM for blk-mq shouldn't be too hard either, but if we don't get rid of the nr_pending counter somehow it would be a severe performance penalty for all scsi devices.
First, tested that next-20170717 still triggers the problem when no extra options given. Adding scsi_mod.use_blk_mq=0 makes tests work.
Then I tried with sd.diff patched next-20170717. Works (still) with use_blk_mq=0. Also works when no options given, so this patch avoids the hang when using the new block-mq.
These tests on generic Haswell 4790K desktop machine. Best regards, Tomi -- Intel Finland Oy - BIC 0357606-4 - Westendinkatu 7, 02160 Espoo
